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. 2023 Jul 31;378(1882):20220122.
doi: 10.1098/rstb.2022.0122. Epub 2023 Jun 12.

Do changes in body mass alter white blood cell profiles and immune function in Australian cane toads (Rhinella marina)?

Gregory P Brown  1 , Cameron M Hudson  2   3 , Richard Shine  1
Affiliations

Do changes in body mass alter white blood cell profiles and immune function in Australian cane toads (Rhinella marina)?

Gregory P Brown et al. Philos Trans R Soc Lond B Biol Sci. .

Abstract

Variation in food resources can result in dramatic fluctuations in the body condition of animals dependent on those resources. Decreases in body mass can disrupt patterns of energy allocation and impose stress, thereby altering immune function. In this study, we investigated links between changes in body mass of captive cane toads (Rhinella marina), their circulating white blood cell populations, and their performance in immune assays. Captive toads that lost weight over a three-month period had increased levels of monocytes and heterophils and reduced levels of eosinophils. Basophil and lymphocyte levels were unrelated to changes in mass. Because individuals that lost mass had higher heterophil levels but stable lymphocyte levels, the ratio of these cell types was also higher, partially consistent with a stress response. Phagocytic ability of whole blood was higher in toads that lost mass, owing to increased circulating levels of phagocytic cells. Other measures of immune performance were unrelated to mass change. These results highlight the challenges faced by invasive species as they expand their range into novel environments which may impose substantial seasonal changes in food availability that were not present in the native range. Individuals facing energy restrictions may shift their immune function towards more economical and general avenues of combating pathogens. This article is part of the theme issue 'Amphibian immunity: stress, disease and ecoimmunology'.

Keywords: Bufo marinus; ecoimmunology; energy budget; leukogram; stress.

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Conflict of interest statement

We declare we have no competing interests.

Figures

Figure 1.
Figure 1.
Representative cane toad (Rhinella marina) blood cell types. Basophil (B), eosinophil (E), heterophil (H), lymphocyte (L), thrombocyte (t) and erythrocyte (r). Bar represents 10 µm. Giemsa stain. (Online version in colour.)
Figure 2.
Figure 2.
Relationship between rate of mass change (% day−1) and phagocytic ability of whole blood. (a) Mean luminescence over 180 min and (b) maximum luminescence recorded over 180 min. y-axis scale is in relative luminescence units (RLU).
Figure 3.
Figure 3.
Relationship between rate of mass change (% day−1) and log-transformed white blood cell concentrations and heterophil : lymphocyte (H : L) ratios.
See this image and copyright information in PMC

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